Exercise Machine With Controlled Motion and User Force Matching Resistance

ABSTRACT

An exercise machine with controlled motion and user force matching resistance. The machine includes a frame to which is rigidly mounted a motor driven reciprocating drive. A user engageable arm is pivotally mounted to the frame. The reciprocating drive is connected to the arm by a rigid connecting rod. The reciprocating drive drives the arm through a predetermined stroke following a pre-determined velocity profile. The user performs the exercise by applying force to the arm. The arm applies a generally equal counterforce to the force applied by the user. The pre-determined motion of the arm is generally independent of the force applied by the user. The stroke of the arm has a fixed fully contracted position and a user adjustable fully extended position. Adjustments to the fully extended position are made by changing the location of the joint between the connecting rod and the arm. Motion of the arm starts upon application of force applied by the user, and stops when the user force is removed.

BACKGROUND Prior Art

Controlled movement exercise with user force matching resistance isrecognized as a highly effective form of exercise since it allows theuser to exert the maximum force he or she is capable of at each positionthroughout the full range of the exercise motion. It is also consideredas among the safest forms of resistance exercise and is employed inmachines used for physical therapy.

Despite these advantages, machines using controlled movement with userforce matching resistance are rarely seen outside rehabilitation clinicsdue to their high cost, complexity and difficulty of adjustment andoperation. Much of the complexity and cost comes from the motion andresistance controlling features themselves, as they include specializedelectro-mechanical actuators, complex feedback features and oftencomputer control in order to provide controlled movement resistance.Many make use of stepper or servo motors which in addition to being moreexpensive than a standard 120 volt single phase electric motor, have theadditional expense of requiring a specialized power supply called anamplifier or driver.

Most of the prior art machines use some form of geared drive between themotor and the output arm. However, there have been some attempts made atproducing a machine using a linkage between the motor and the outputarm, but all have had shortcomings. U.S. Pat. No. 4,635,933 to Schnell(1987) shows one such attempt using a crank mechanism driven by anelectric motor. However, the design specifies that the electric motor bea reversible variable speed/variable torque type motor, which willrequire a control circuit to control the motor thereby adding to theexpense of the machine. The means of adjusting the output stroke shown,simply changing the length of the crank or rocker arms, willsimultaneously change the starting and ending points of the exercisestroke, likely causing the user to have to change position. The startingand stopping of the machine is in control of the user and is performedby an action of a body part, such as a hand or foot, which is not beingexercised.

U.S. Pat. No. 4,884,801 to Schnell (1989) shows another device using aflexible transmission member attached to a motor-driven crank to auser-actuated member. However, this device requires that the useractivate the motor by the separate act of activating a switch either byhand or foot. There is also no provision to have the motor-driven crankstop or start in any particular position to allow for ease of adjustmentor having a definite starting point to begin the exercise. Also, removalof the user force does not stop the motor. Furthermore, the strokeadjustment means shown will simultaneously change the starting andending points of the exercise stroke, likely causing the user to have tochange position.

Advantages

Accordingly several advantages of one or more aspects are as follows: toprovide an exercise device with controlled motion and user forcematching resistance in which the motion and resistance features aredriven by a standard 120 volt single phase electric motor, whichsupplies resistance in response to force generated by the userregardless of magnitude or fluctuation, which starts automatically onapplication of user force and stops automatically on removal of userforce, which allows the user to perform both concentric and eccentriccontractions, which does not require feedback or computer controls toprovide resistance and maintain velocity, in which forced concentriccontractions and eccentric contractions may be safely performed withouta spotter, in which eccentric contractions only training is possiblewithout a spotter, and which is simple for the user to adjust andoperate. Other advantages of one or more aspects will be apparent from aconsideration of the drawings and ensuing description.

DRAWINGS Figures

FIG. 1 shows a perspective view of an exercise machine in accordancewith a first embodiment.

FIG. 2 shows a perspective view of the frame subassembly from the firstembodiment.

FIG. 3 shows an exploded view of the adjustable seat subassembly fromthe first embodiment.

FIG. 4 shows an exploded view of the exercise arm subassembly from thefirst embodiment.

FIG. 5 shows an exploded detail view from FIG. 4.

FIG. 6 shows a perspective view of the reciprocating drive from thefirst embodiment.

FIG. 7 shows a perspective view of the reciprocating mechanism from thefirst embodiment.

FIG. 8 shows a rear perspective view of the reciprocating mechanism fromthe first embodiment.

FIG. 9 shows a perspective view of the connecting rod subassembly fromthe first embodiment.

FIG. 10 shows the connecting rod subassembly connections from the firstembodiment.

FIG. 11 shows a perspective view of the control panel subassembly fromthe first embodiment.

FIG. 12 shows an electrical schematic of the operating circuit from thefirst embodiment.

FIG. 13 shows a block diagram detailing force measured and displayedfrom the first embodiment.

FIG. 14 shows the user seated in the exercise machine from the firstembodiment with the exercise arm in the fully contracted position.

FIG. 15 shows the user seated in the exercise machine from the firstembodiment with the exercise arm in the fully extended position.

FIG. 16 shows a perspective view of an exercise machine in accordancewith a second embodiment.

FIG. 17 shows a perspective view of an exercise machine in accordancewith a third embodiment.

FIG. 18 shows a perspective view of a reciprocating mechanism inaccordance with a second embodiment.

FIG. 19 shows a perspective view of a reciprocating mechanism inaccordance with a third embodiment.

FIG. 20 shows a perspective view of a reciprocating mechanism inaccordance with a fourth embodiment.

FIG. 21 shows a perspective view of a reciprocating mechanism inaccordance with a fifth embodiment.

FIG. 22 shows a perspective view of a reciprocating mechanism inaccordance with a sixth embodiment.

DETAILED DESCRIPTION FIGS. 1 Through 15—First Embodiment

A first embodiment of the exercise machine, designated broadly as 10, isillustrated in FIG. 1. In this embodiment machine 10 is configured toperform a chest press exercise. Machine 10 includes a base or framesubassembly 12 to which is slidably connected an adjustable user supportor seat subassembly 14. An exercise arm subassembly 16 is pivotallyconnected to frame 12. A reciprocating drive subassembly 18 is fixedlyconnected to frame 12. A control panel subassembly 20 is pivotallyconnected to frame 12. The output of drive subassembly 18 is connectedto arm subassembly 16 by a link or connecting rod subassembly 22. Thesecomponents are described in detail below.

Referring to FIG. 2, frame 12 includes a group of longitudinal framemembers 24A, 24B and 24C. Member 24B includes a series of holes 26.Holes 26 extend through both vertical faces of member 24B, and are usedin adjusting the longitudinal position of seat subassembly 14. Members24A, 24B and 24C are rigidly and fixedly connected to a transverse framemember 28A and a transverse frame member 28B. A group of threaded holes30 through the top horizontal faces of members 24A, 24B and 28B are usedto attach drive subassembly 18 to frame 12. These assembled members areheld off the floor by a group of feet 32. A threaded hole 34 is locatedat two places on the front vertical face of member 28A. Holes 34 areused to attach a pair of split bearing assemblies 36. Each bearingsubassembly 36 includes a bearing base section 38 having a set ofthrough holes 40 and a bearing top section 42 having a set of throughholes 44. Both base section 38 and bearing top 42 have ahalf-cylindrical cut bearing surface 46. A set of bolts 48 pass throughholes 44 in bearing top 42, holes 40 in base section 38 and into holes34, securing bearing assemblies 36 to member 28A.

FIG. 3 shows details of seat subassembly 14 which includes a back rest52 connected to an upright column 54 using a set of bolts 56 through agroup of holes 58 into threaded holes (not shown) in the rear face ofback rest 52. A seat holder bracket 60 is fixedly connected to the lowerportion of column 54. Bracket 60 includes a hole 62 that extends throughboth sides of bracket 60. A seat adjustment bar 64 containing a group ofadjustment holes 66 extending through both vertical side faces and agroup of holes 68 in the top surface, is fixedly connected to theunderside of a seat bottom 70 by a set of bolts 72 which go throughholes 68 into a group of threaded holes (not shown) in the bottom faceof seat bottom 70. A seat adjustment pin 74 extends through hole 62 inbracket 60 and one of holes 66 in bar 64. A carriage 76 is fixed to thebottom of column 54. Carriage 76 has a hole 78 extending through bothsides of carriage 76 and a set of holes 80 extending through both sidesof carriage 76. A pair of rods 82 extends through holes 80. Rods 82 havea groove 84 at each end. An e-clip 86 fits into groove 84 at each end tohold rods 82 in carriage 76. Carriage 76 is slidably mounted on member24B. Downward and sideways motion of carriage 76 is prevented by thebody of carriage 76, while upward motion is prevented by rods 82.Carriage 76, and thereby seat subassembly 14, can slide along the lengthof member 24B. To secure the position of seat subassembly 14, a pin 88is inserted through hole 78 in carriage 76 and into one of holes 26 inmember 24B.

Referring to FIGS. 4-5, arm subassembly 16 includes an arm tube 90having a lower horizontal section, two vertical sections and twocollinear upper horizontal sections separated by a gap. A group offlanges 92A, 92B and 92C are fixedly attached to the lower horizontalsection of tube 90. Flange 92C has a series of through holes 94 laid outin a circular pattern. A pair of strain gauges 96A and 96B is mounted onthe front surface of one vertical section of tube 90. A second pair ofstrain gauges 96C and 96D (not shown) is mounted directly behind thefirst pair on the rear surface of the same vertical section of tube 90.A pair of strain gauges 96E and 96F is mounted on the front surface ofthe opposite vertical section of tube 90. A second pair of strain gauges96G and 96H (not shown) is mounted directly behind the first pair on therear surface of the same vertical section of tube 90. An adjustmentplate 98 has a series of tapped holes 100 laid out in a circularpattern, and a cutout 102 which allows it to fit over the lowerhorizontal section of tube 90. Plate 98 is attached to flange 92C usingbolts 104. Plate 98 has a circular arc shaped channel 106 with a seriesof through holes 108 running along the center of the channel, and tappedholes 110 in the top surface. A cap 112 has a pair of through holes 114and is mounted to the top of plate 98 with a pair of bolts 116.

Referring to FIG. 6, drive subassembly 18 includes an electric motor118, a speed reducer 120, a stand 122 and a reciprocating mechanismsubassembly 124. Speed reducer 120 is mounted to stand 122 using bolts(not shown). Stand 122, motor 118 and mechanism 124 are mounted on abase plate 126 using bolts partially shown. A drive pulley 128 ismounted on the output shaft of motor 118. A driven pulley 130 is mountedon the input shaft of speed reducer 120. Drive pulley 128 drives drivenpulley 130 through a flexible belt 132.

Referring to FIGS. 7 and 8, mechanism 124 includes a guide rail 134,supported by a front post 136A and a rear post 136B. Rail 134 isattached to post 136A and post 136B by a pair of bolts 138. A set ofthrough holes 140 in the bottom flange of post 136A and post 136B allowmechanism 124 to be attached to plate 126. A carriage 142 is slidablyfixed over rail 134. The outside vertical face of carriage 142 includesa stud 144A, a stud 144B and stud 144C. An activation lever 146 containsa stud 148A, a stud 148B and a stud 148C. Lever 146 is pivotally mountedon stud 144A and is held in place by an e-ring clip 150. A limit switch152A is mounted to the outside face of post 136A using a set of screws154. A limit switch 152B is mounted to the outside face of post 136Busing screws 154. A limit switch 152C is mounted to the top face of rail134 using screws 154. An extension spring 156 is connected between stud144B and stud 148A. The inside vertical face of carriage 142 contains aslot 158. A hub 160 is connected to a crank arm 162 which has a camroller 164 mounted to its end. Roller 164 rides in slot 158. Hub 160 ismounted on the output shaft of reducer 120.

Referring to FIG. 9, rod subassembly 22 includes a tube 166 at the frontend of which is connected a yoke 168. Yoke 168 includes a through hole170 and a slot 172. A pair of cylindrical projections 174A and 174B areconcentric to hole 174 and project a short distance past the insidefaces of slot 172. A flat end 176 is attached to the rear end of tube166. A through hole 178 is located at the rear end of end 176.

FIG. 10 shows how the output of mechanism 124 is transmitted to armsubassembly 16 through rod subassembly 22. Flat end 176 is pivotallymounted on stud 148B and is secured in place by an e-clip 180.Cylindrical Projections 174A and 174B ride in channel 106. The locationof yoke 168 along channel 106 is selected by a locating pin 182.Referring to FIG. 11, control panel subassembly 20 includes a controlbox 184 which is mounted to a support tube 186. Tube 186 is pivotallymounted on support stud 50. Box 184 includes a display screen 188, athree position DPDT control switch 190, and a pair of normally openmomentary push button switches 192A and 192B.

FIG. 12 shows a control circuit schematic 194 which controls theoperation of machine 10. Components of circuit 194 contained in box 184include a transformer 196 and a low voltage relay 198. Circuit 194 issupplied with a standard AC voltage source 200. Transformer 196 stepsdown the supplied 120 VAC to a safe lower level. Relay 198 operates atthe low voltage supplied by transformer 196 and is capable of switchingthe supplied 120 VAC. Components of circuit 194 external to box 184include switch 190, switches 192A and 192B, switches 152A, 152B and152C, and motor 118.

Referring to FIG. 13, a display output diagram 202 is shown whichdetails the operation of the display. Diagram 202 includes componentsinternal and external to box 184. External components include straingauges 96A, 96B, 96C and 96D, connected to form a whetstone bridge 202A,and strain gauges 96E, 96F, 96G and 96H, connected to form a secondwhetstone bridge 202B. A source of electrical potential V supplies theexcitation voltage to bridges 202A and 202B. Internal components includea pair of amplifiers 204A and 204B, a pair of analog to digitalconverters 206A and 206B, a micro-processer 208 and a multifunctiondisplay 210. The arrangement shown in FIG. 13 is well known in the art.

Operation

Referring now to FIGS. 1, thru 15, to use machine 10, a user 212 firsttakes position in seat subassembly 14 as shown in FIG. 14: seated onseat bottom 70 with his or her back against back rest 52. Seatsubassembly 14 acts as a positioning system to allow adjustment of theposition of user 212 relative to the arm subassembly 16. If controlpanel subassembly 20 is positioned in front of seat subassembly 14, user212 can rotate control panel subassembly 20 to one side to gain accessto seat bottom 70. Once seated, user 212 rotates control panelsubassembly 20 to its position in front of seat subassembly 14. Toperform the exercise, user 212 first adjusts the position of seatsubassembly 14 to suit user 212's seated shoulder height and reach. Tobegin these adjustments arm subassembly 16 should be in the fullycontracted position, referred to as the initial position. If armsubassembly 16 is not already in this position, it may be moved there byplacing control switch 190 into the adjustment mode position andpressing and holding switch 192B. This action supplies low voltage DCpower to relay 198, which is activated and provides 120 VAC power tomotor 118. At this point drive subassembly 18 resumes its cycle atwhatever point it stopped at previously, meaning that it may first causearm subassembly 16 to move towards the fully extended position beforemoving towards the fully contracted position. Once arm subassembly 16moves near its fully contracted position, carriage 142 contacts andactivates limit switch 152B, opening the circuit, removing power fromrelay 198, which removes 120 VAC power from motor 118. There will besome rotational inertia of motor 118 that will continue to move drivesubassembly 18 and hence arm subassembly 16 slightly further. Theactivation point of limit switch 152B can be adjusted to account forthis additional motion, so that the final stopping point is as close tothe fully contracted position as possible. Alternately anelectromagnetic brake may be added to quickly stop motor 118's rotation.

Once arm subassembly 16 is in the fully contracted position, seatsubassembly 14 adjustment can be achieved. User 212 adjusts the verticalposition of seat subassembly 14 to a comfortable position to grasp upperhorizontal portions of tube 90. This will put user 212's shoulder jointgenerally even with the upper horizontal sections of tube 90. Thisadjustment is accomplished by removing pin 74 from bracket 60, movingseat bottom 70 and attached bar 64 up or down as required, and replacingpin 74 back through hole 62 in bracket 60 and hole 66 in bar 64 closestto the desired position. User 212 then adjusts the front to backposition of seat subassembly 14 to a comfortable position to grasp upperhorizontal sections of tube 90 as close to user 212's chest as iscomfortable. This adjustment is accomplished by removing pin 88 fromhole 78, moving seat subassembly 14 to the rear or front as required,and replacing pin 88 through hole 78 in carriage 76 and hole 26 inmember 24B closest to the desired position. This type of adjustable seatis well known in the art.

The adjustments of seat subassembly 14 being completed, user 212 nextadjusts the fully extended point of the stroke of arm subassembly 16.With control switch 190 in the adjustment mode position user 212 pressesand holds adjustment switch 192A. This action supplies low voltage DCpower to relay 198, which is activated and provides 120 VAC power tomotor 118. At this point drive subassembly 18 resumes its cycle atwhatever point it stopped at previously, meaning that it may first causearm subassembly 16 to move towards the fully contracted position beforemoving towards the fully extended position. Once arm subassembly 16moves near its fully extended position, carriage 142 contacts andactivates limit switch 152A, opening the circuit, removing power fromrelay 198, which removes 120 VAC power from motor 118. There will besome rotational inertia of motor 118 that will continue to move drivesubassembly 18 and hence arm subassembly 16 slightly further. Theactivation point of limit switch 152A can be adjusted to account forthis additional motion, so that the final stopping point is as close tothe fully extended position as possible. Alternately an electromagneticbrake may be added to quickly stop motor 118's rotation.

At this point user 212 adjusts the fully extended position of armsubassembly 16 to a comfortable position. Ideally this position willallow user 212, with his or her back firmly against back rest 52 andapplying considerable force against the upper horizontal sections oftube 90, close to full extension of his or her arms without locking theelbows, as depicted in FIG. 15. This adjustment is accomplished byremoving pin 182 from hole 170 and moving yoke 168 of rod subassembly 22up or down in channel 106. Moving yoke 168 up will move arm subassembly16 towards user 212, resulting in a shorter total stroke. Moving yoke168 down will move arm subassembly 16 away from user 212, resulting in alonger total stroke. Once the desired fully extended position of armsubassembly 16 is determined, pin 182 is reinserted into hole 170 inyoke 168 and hole 108 in plate 98 closest to the desired position. Thisadjustment of the fully extended position of arm subassembly 16 does notaffect the fully contracted position of arm subassembly 16 therebyrequiring no adjustments of seat subassembly 14. This is because thepattern of adjustment holes 108 in plate 98 are located on an circulararc, the radius of which is equal to the distance between holes 178 and170 of rod subassembly 22, and the center of which is concentric withstud 148B when arm subassembly 16 is in the fully contracted position.This means that once the initial seat adjustments are made, they do notneed to be further adjusted for changes to the fully extended positionof arm subassembly 16. This design feature allows an alternative methodof fully extended position adjustment. If user 212 has used machine 10in the past and is familiar with the desired fully extended position ofarm subassembly 16, the fully extended position may be set while armsubassembly 16 is in the fully contracted position by removing pin 182from hole 170 and moving yoke 168 of rod subassembly 22 up or down inchannel 106 until hole 170 lines up with the pre-known hole 108 inchannel 106.

Once seat subassembly 14 and arm subassembly 16 are adjusted, user 212could choose to follow the steps outlined above and return armsubassembly 16 to the start position prior to beginning the exercise, oruser 212 could begin the exercise from the fully extended position ofarm subassembly 16. To begin the exercise, user 212 places controlswitch 190 into the ON position. With user 212's back against back rest52, user 212 then grasps the two collinear upper horizontal sections ofarm subassembly 16 and pushes them away from the his or her body. Seatsubassembly 14 acts as a buttress to counter the user force applied toarm subassembly 16 and keep user 212 in place. The force applied by user212 creates tensile force in rod 22 which transmits the force to lever146. The force must be sufficient to overcome the pre-loaded tension inspring 156. This pre-load is selected to provide a means toautomatically shut off power to electric motor 118 and hence the motionof arm subassembly 16 once user 212 removes force from arm subassembly16, and to prevent inadvertent low force contact with arm subassembly 16from starting the machine at an undesirable time. Once this initialforce is overcome, rod subassembly 22 pulls lever 146 against stud 144D.This movement forces stud 148C into limit switch 152C. This completesthe circuit supplying low voltage DC to relay 198 which thereby supplies120 VAC to electric motor 118. This causes drive subassembly 18 to begincycling through its motion, driving the stroke of arm subassembly 16.Arm subassembly 16 will continue to cycle between the positions of FIGS.14 and 15 as long as sufficient force is applied by user 212 to overcomethe preloaded force in spring 156. As a consequence user 212 can startout the exercise with his or her full strength and continue until user212's strength is insufficient to overcome the pre-loaded tension inspring 156. The power output of motor 118 is chosen so that therotational speed of the motor 118 and reducer 120, and hence the cyclespeed of mechanism 124 do not vary significantly regardless of the forceapplied by user 212 to arm subassembly 16. In addition, the cycle speedis chosen so that from the aspect of user 212, the movement may beconsidered quasi-static, resulting in a natural reaction force generatedby machine 10 through arm subassembly 16 that has the same magnitude butthe opposite direction of the force applied by user 212. User 212 mayalso chose to apply the minimum force necessary to overcome thepre-loaded tension in spring 156 during the movement of arm subassembly16 towards the fully extended position, and then apply full availablestrength during the movement of arm subassembly 16 towards the fullycontracted position. This would constitute an eccentric contractionsonly exercise; know commonly in resistance training as negatives. Theseeccentric only contractions can also be added at the end of aconcentric/eccentric exercise once the muscles become too exhausted toperform concentric contractions. These eccentric only or eccentric onlyafter exhaustion movements are normally performed with the aid of aspotter who supplies the needed additional force to perform theconcentric contraction, while allowing user 212 to perform the eccentricportion.

FIGS. 16-17 Alternate Embodiments

A second embodiment of the exercise machine, designated broadly as 214,is illustrated in FIG. 16. In this embodiment machine 214 is configuredto perform a shoulder press exercise. As shown in FIG. 16, machine 214contains seat subassembly 14, arm subassembly 16, drive subassembly 18,control panel subassembly 20 and connecting rod subassembly 22. Thesesubassemblies have the same form and function as in the first embodimentdescribed above. The only substantial difference in form is in the framesubassembly, herein designated as 12′. The frame members have beenrearranged and additional members added to facilitate the differentexercise movement.

A third embodiment of the exercise machine, designated broadly as 216,is illustrated in FIG. 17. In this embodiment machine 216 is configuredto perform a leg press exercise. As shown in FIG. 17, machine 216contains seat subassembly 14, drive subassembly 18, control panelsubassembly 20 and connecting rod subassembly 22. These subassemblieshave the same form and function as in the first embodiment describedabove. The only substantial differences in form are in the framesubassembly, herein designated as 12″, and the arm subassembly, hereindesignated as 16′. As in the second embodiment above, the frame membersin the third embodiment have been rearranged and additional membersadded to facilitate the different exercise movement. The arm subassemblyhas been reconfigured to interact with the user's feet.

FIGS. 18-22 Additional Embodiments

Additional embodiments of some subassemblies of the machine can provideadditional capabilities. For example, in FIG. 18 studs 144B, 144C, and144D, switch 152C and spring 156 in mechanism 124 are replaced withstuds 144B′, 144C′, and 144D′, switch 152C′ and spring 156′. Switch152C′ is wired in circuit 194 just as switch 152C is. With thesechanges, application of a compressive force on rod 22 rather than atensile force on rod 22 will rotate lever 146 toward switch 152C′,forcing stud 148C into switch 152C′ to activate circuit 194. Thisembodiment of mechanism 124 is designated broadly by 124′ in FIG. 18. Ifmechanism 124 in machine 214 is replaced with mechanism 124′ thenmachine 214 embodiment becomes a pull down exercise machine embodiment.

Similarly in machine 10 embodiment shown in FIG. 1, if seat subassembly14 is rotated 180 degrees about its vertical axis, and mechanism 124 isreplaced with mechanism 124′, machine 10 embodiment becomes a rowingexercise machine embodiment.

Additionally, mechanism 124 may be configured as shown in FIG. 19. Inthis configuration studs 144B and 144C, switch 152C and Spring 156 arecombined with studs 144B′, and 144D′, switch 152C′ and spring 156′.Lever 146 is balanced between the two pre-tensioned springs 156 and 156′such that rotation of lever 146 is resisted in both directions. Studs144C and 144D′ are positioned to allow sufficient movement of lever 146in both directions so that full movement in one direction causes stud148C to activate switch 152C while full movement in the oppositedirection causes stud 148C to activate switch 152C′. Switch 152C′ iswired in parallel with switch 152C so that activation of either switch152C or switch 152C′ will activate circuit 194. This embodiment ofmechanism 124 is designated broadly by 124″ in FIG. 19. If mechanism 124is replaced with mechanism 124″ in machine 10, then machine 10 becomes acombination chest press and rowing machine. If mechanism 124 is replacedwith mechanism 124″ in machine 214, then machine 214 becomes acombination shoulder press and pull down machine. Mechanism 124 in FIGS.7 and 8 may be modified to include a cam 218 and a follower 220 as shownin FIG. 20, a face cam 222 and follower 220 as shown in FIG. 21, or asix bar linkage 224 as shown in FIG. 22.

CONCLUSION, RAMIFICATIONS AND SCOPE

Accordingly, the reader will see that the exercise machines of thevarious embodiments will provide exercise for the user that has bothcontrolled motion that does not vary significantly regardless of theforce applied by the user, and supplies a resistance as a consequence ofthe natural reactive force that matches the force applied by the user,regardless of magnitude or fluctuation. Furthermore, the exercisemachine has the additional advantages in that:

-   -   it is powered by a standard 120 volt single phase electric        motor;    -   it starts automatically on application of user force and stops        automatically on removal of user force;    -   it allows the user to perform both concentric and eccentric        contractions;    -   it does not require feedback or computer controls to provide        resistance and maintain velocity;    -   it allows forced concentric contractions and eccentric        contractions may be safely performed without a spotter;    -   it allows eccentric contraction only training without a spotter;    -   it is simple for the user to adjust and operate.

While the above description contains many specificities, these shouldnot be construed as limitations on the scope of the embodiments but asmerely providing illustration of some of several embodiments. Forexample frame 12 may include additional members, certain components maybe formed from multiple pieces, motor 118 may be directly connected tospeed reducer 120, or motor 118 may be integrated with speed reducer 120forming a gearmotor. Thus the scope of the embodiments the should bedetermined by the appended claims and their legal equivalents, ratherthan by the examples given.

That which is claimed is:
 1. An exercise machine, comprising in combination: a frame; an arm pivotally connected to said frame, configured to engage an exercising user; a reciprocating drive means for driving said arm, said reciprocating drive means being fixedly mounted to said frame; a rigid connecting means for connecting said arm and said reciprocating drive means so that movement of said reciprocating drive means causes said arm to move in response thereto, said arm being constrained thereby to move along a stroke path between a fully contracted position closest to said user, and a fully extended position furthest from said user, said fully contracted position being fixed and said fully extended position being adjustable; and adjustment means for adjusting said fully extended position of said arm without changing said fully contracted position.
 2. The exercise machine defined in claim 1, wherein said user achieves exercise by applying force against said arm during movement of said arm along said stroke path.
 3. The exercise machine defined in claim 1, wherein said reciprocating drive means includes an electric motor operatively connected to a mechanical speed reducer which is operatively connected to a reciprocating mechanism, said reciprocating mechanism providing the output of said reciprocating drive means.
 4. The exercise machine defined in claim 3, wherein the output power of said electric motor is predetermined such that a generally constant rotational speed is maintained, generally irrespective of the force applied to said arm by said user.
 5. The exercise machine defined in claim 3 wherein said reciprocating mechanism includes a mechanism selected from the group consisting of a scotch yoke mechanism, a cam and cam follower, a face cam and cam follower, and a six bar linkage.
 6. The exercise machine defined in claim 1, wherein said reciprocating drive means provides a predetermined generally equal duration of the extension and contraction strokes of said arm.
 7. The exercise machine defined in claim 1, wherein said reciprocating drive means provides a predetermined unequal duration of the extension and contraction strokes of said arm.
 8. The exercise machine defined in claim 1, wherein said reciprocating drive means is activated upon said user applying a predetermined force against said arm.
 9. The exercise machine defined in claim 1, wherein said reciprocating drive means is deactivated upon said user removing applied force against said arm.
 10. The exercise machine defined in claim 1, further including a bracing means for holding said user in a selected position relative to said arm and counteracting force exerted by said user upon said arm, said bracing means being slidably mounted to said frame, the position of said bracing means being adjustable in relation to said arm and fixable once desired position is reached.
 11. The exercise machine defined in claim 1, wherein a positioning means allows the user to activate said reciprocating drive means to move said arm to either said fully extended position and have it stop there or to said fully contracted position and have it stop there.
 12. The exercise machine defined in claim 1, wherein said adjustment means is comprised of a first attachment point of said rigid connecting means being pivotally connected to the output of said reciprocating drive means and a second attachment point of said rigid connecting means being slidably and pivotally connected to an element of said arm, said element having multiple attachment points laid out in a circular arc such that the radius of said circular arc is equal to the distance between said first attachment point of said rigid connecting means and said second attachment point of said rigid connecting means and the center point of said circular arc coincides with said connection between said first attachment point of said rigid connecting means and said output of said reciprocating drive means when said arm is in said fully contracted position, wherein adjustment is achieved by changing said connection of said second attachment point of said rigid connecting means from the existing said attachment point of said element of said arm to a nonidentical attachment point of said element of said arm selected from said multiple attachment points on said element of said arm.
 13. An exercise machine, comprising in combination: a frame; an arm pivotally connected to said frame, configured to engage an exercising user; a reciprocating drive fixedly mounted to said frame, said drive including an electric motor operatively connected to a mechanical speed reducer the output of which is operatively connected a reciprocating mechanism, wherein said reciprocating mechanism provides the output of said reciprocating drive; a rigid connecting rod having a first attachment point and a second attachment point separated by a predetermined distance for connecting the output of said reciprocating drive to said arm so that movement of said reciprocating drive causes said arm to move in response thereto, said arm being constrained thereby to move along a stroke path between a fully contracted position closest to said user, and a fully extended position furthest from said user, said fully contracted position being fixed and said fully extended position being adjustable; a adjustment feature for adjusting said fully extended position of said arm without changing said fully contracted position, said adjustment feature comprising said first attachment point of said rigid connecting rod being pivotally connected to said output of said reciprocating drive and said second attachment point of said rigid connecting rod being slidably and pivotally connected to an element of said arm, said element having multiple attachment points laid out in a circular arc such that the radius of said circular arc equal to the distance between said first attachment point of said rigid connecting rod and said second attachment point of said rigid connecting rod and the center point of said circular arc coincides with said connection between said first attachment point of said rigid connecting rod and said output of said reciprocating drive when said arm is in said fully contracted position, wherein adjustment is achieved by changing said connection of said second attachment point of said rigid connecting rod from the existing said attachment point of said element of said arm to a nonidentical attachment point of said element of said arm selected from said multiple attachment points on said element of said arm; and a seat slidably mounted to said frame for receiving said user and countering force applied to said arm by said user, said seat including a seat bottom for said user to sit upon and a backrest for supporting the back of said user, the position of said seat being adjustable in a generally horizontal plane in a direction generally perpendicular to the pivotal axis of said arm and said seat bottom being adjustable in a generally vertical plane, said position of said seat being fixable once desired position is reached.
 14. The device defined in claim 13, wherein the output power of said electric motor is predetermined such that a generally constant rotational speed is maintained, generally irrespective of the force applied to said arm by said user.
 15. The device defined in claim 13 wherein said reciprocating mechanism includes a mechanism selected from the group consisting of a scotch yoke mechanism, a cam and cam follower, a face cam and cam follower, and a six bar linkage.
 16. The device defined in claim 13, wherein said reciprocating drive provides a predetermined generally equal duration of the extension and contraction strokes of said arm.
 17. The exercise machine defined in claim 13, wherein said reciprocating drive provides a predetermined unequal duration of the extension and contraction strokes of said arm.
 18. An exercise machine, comprising in combination: a frame; an arm pivotally connected to said frame, configured to engage an exercising user; a reciprocating drive means for driving said arm, said reciprocating drive means being fixedly mounted to said frame; a rigid connecting means for connecting said arm and said reciprocating drive means by having a first attachment point connected to the output of said reciprocating drive and a second attachment point connected to an element of said arm, so that movement of said reciprocating drive means causes said arm to move in response thereto, said arm being constrained thereby to move along a stroke path between a fully contracted position closest to said user, and a fully extended position furthest from said user, said fully contracted position being fixed and said fully extended position being adjustable; adjustment means for adjusting said fully extended position of said arm without changing said fully contracted position, said adjustment means comprising said first attachment point of said rigid connecting means being pivotally connected to said output of said reciprocating drive means and said second attachment point of said rigid connecting means being slidably and pivotally connected to an element of said arm, said element having multiple attachment points laid out in a circular arc such that the radius of said circular arc is equal to said distance between said first attachment point of said rigid connecting means and said second attachment point of said rigid connecting means, and the center point of said circular arc coincides with said connection of said first attachment point of said rigid connecting means to said output of said reciprocating drive means when said arm is in said fully contracted position, wherein adjustment is achieved by changing existing said connecting of said second attachment point of said rigid connecting means from the existing said attachment point of said element of said arm to a nonidentical attachment point of said element of said arm selected from said multiple attachment points on said element of said arm; and a user support means for receiving said user and countering force applied to said arm by said user, said user support means being slidably mounted to said frame, the position of said user support means being adjustable in relation to said arm and fixable once desired position is reached.
 19. The device defined in claim 18, wherein said reciprocating drive means provides a predetermined generally equal duration of the extension and contraction strokes of said arm.
 20. The exercise machine defined in claim 18, wherein said reciprocating drive means provides a predetermined unequal duration of the extension and contraction strokes of said arm. 